Async Elevation Query Example

gistfile1.txt

/* -*-c++-*- */
/* osgEarth - Dynamic map generation toolkit for OpenSceneGraph
* Copyright 2016 Pelican Mapping
* http://osgearth.org
*
* osgEarth is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program.  If not, see <http://www.gnu.org/licenses/>
*/

#include <osgViewer/Viewer>
#include <osgEarth/Notify>
#include <osgEarthUtil/EarthManipulator>
#include <osgEarthUtil/ExampleResources>
#include <osgEarth/MapNode>
#include <osgEarth/ThreadingUtils>
#include <osgEarth/Metrics>
#include <osgEarth/Registry>
#include <osgEarthUtil/Controls>

#define LC "[async] "

using namespace osgEarth;
using namespace osgEarth::Util;
using namespace osgEarth::Util::Controls;
using namespace osgEarth::Threading;

namespace ui = osgEarth::Util::Controls;

/**
 * Demonstrates how to use the asynchronous ElevationPool::getElevation
 * method, which uses the Promise/Future pattern.
 */

int
usage(const char* name)
{
    OE_NOTICE 
        << "\nUsage: " << name << " file.earth" << std::endl
        << MapNodeHelper().usage() << std::endl;

    return 0;
}


struct App
{
    osg::ref_ptr<MapNode> _mapNode;
    osg::ref_ptr<ui::LabelControl> _debugLabel;
    osg::ref_ptr<ui::LabelControl> _resultLabel;
    
    App()
    {
        _debugLabel = new LabelControl("Debug");
        _resultLabel = new LabelControl("Result");
    }
};

struct QueryElevationUnderMouse : public osgGA::GUIEventHandler
{
    App& _app;

    QueryElevationUnderMouse(App& app) : _app(app) { }

    bool handle(const osgGA::GUIEventAdapter& ea, osgGA::GUIActionAdapter& aa)
    {
        if (ea.getEventType() == ea.MOVE)
        {
            osg::Vec3d world;
            _app._mapNode->getTerrain()->getWorldCoordsUnderMouse(aa.asView(), ea.getX(), ea.getY(), world);
            GeoPoint point;
            point.fromWorld(_app._mapNode->getMapSRS(), world);
            _result = _app._mapNode->getMap()->getElevationPool()->getElevation(point);
            return true;
        }

        else if (ea.getEventType() == ea.FRAME)
        {
            if (_result.isAvailable())
            {
                osg::ref_ptr<ElevationSample> sample = _result.release();
                if (sample.valid())
                {
                    _app._resultLabel->setText(Stringify() <<"Elevation=" << sample->elevation << ", Resolution=" << sample->resolution);
                }
            }
        }

        return false;
    }
    Future<ElevationSample> _result;
};

int
main(int argc, char** argv)
{
    osg::ArgumentParser arguments(&argc,argv);

    // help?
    if ( arguments.read("--help") )
        return usage(argv[0]);

    // create a viewer:
    osgViewer::Viewer viewer(arguments);
    viewer.getDatabasePager()->setUnrefImageDataAfterApplyPolicy( true, false );
    viewer.setCameraManipulator( new EarthManipulator(arguments) );

    // load an earth file, and support all or our example command-line options
    // and earth file <external> tags    
    osg::Node* node = MapNodeHelper().load(arguments, &viewer);
    if ( node )
    {
        App app;
        app._mapNode = MapNode::get(node);
        ui::VBox* box = new ui::VBox();
        box->setVertAlign(ui::Control::ALIGN_BOTTOM);
        box->addControl(app._debugLabel.get());
        box->addControl(app._resultLabel.get());
        ui::ControlCanvas::get(&viewer)->addControl(box);
        viewer.setSceneData( node );
        viewer.addEventHandler(new QueryElevationUnderMouse(app));
        Metrics::run(viewer);
    }
    else
    {
        return usage(argv[0]);
    }

    return 0;
}